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Phosphorus oxychloride is a colourless liquid. Its formula is POCl3. It is an inorganic compound. At room temperature & pressure, this compound is a colourless liquid that forms fumes in moist air. It is manufactured in industries on a large scale. At room temperature, this compound is a dull fluid that structures exhaust in clammy air. This exhaust is discharged in light because this compound exhaust with hydrolysis within the sight of dampness. Phosphoryl chloride was first reported by a French chemist Adolphe Wurtz in 1847 by reacting Phosphorus pentachloride with water. Phosphorus oxychloride compound is mostly used in the industrial manufacture of phosphate esters and is also a semiconductor of a safe source of liquid phosphorus used in the diffusion process.
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Key Takeaways: POCl3, Preparation of POCl3, Structure of POCl3.
What is Phosphorus oxychloride, POCl3?
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POCl3 is an inorganic compound. It is commonly referred to as phosphorus oxychloride and also as phosphoryl chloride. It is a colourless liquid. At room temperature, this compound is a liquid that forms fumes. The fumes are released because POCl3 undergoes hydrolysis in presence of moisture. It yields phosphoric acid and hydrogen chloride.
Phosphorus Oxychloride
Preparation Of POCl3
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When PCl3 undergoes oxidation with dioxygen it yields phosphorus oxychloride as the product. Its chemical equation is
2PCl3 + O2 → 2POCl3
Another compound can also be prepared from phosphorus trichloride by treating it with potassium chlorate. Its chemical equation is
3PCl3 + KClO3 → KCl + 3POCl3
It can also be prepared by reacting phosphorus pentachloride with phosphorus pentoxide. Its chemical equation is
P4O10 + 6PCl5 → 10POCl3
Uses of Phosphorus oxychloride
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The uses of phosphorus oxychloride, POCl3 are:
- It is utilized in the semiconductor business as a protected wellspring of fluid phosphorus.
- It is used in the mechanical assembling of phosphate esters.
- It is used as a drying out operator in the Bischler- Napieralski response.
- it is also used as a drying out operator in the concoction research facility. It is utilized as a getting dried out operator in management nitrites from essential amides.
- It is used in the semiconductor industry as a safe source in the diffusion processes of liquid phosphorus.
Structure of POCl3
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The molecule's features contains 3 phosphorus- chlorine single bonds and one phosphorus-oxygen double bond. This molecule is in a tetrahedral shape. The average bond lengths in the crystal structure are 1.98 Å for P–Cl and 1.46 Å for P=O.
Structure of POCl3
From the diagram, it can be noted that the P=O bond is much stronger than the P-Cl bond. P=O bond has a bond length of 158 pm whereas P-Cl bond has a bond length of 202 pm.
Properties of Phosphorus Oxychloride
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The properties of POCl3 are as given below:
Physical Properties
- It is a lacklustre fluid; it has a smelly and impactful scent.
- Its molar mass is 153.33 grams per mole.
- It is in a fluid state and its thickness is 1.645 grams per cubic centimetre.
- The breaking point of this compound is 378.9K and the liquefying point is 274.4K. The fluid scope of phosphorus oxychloride is like that of water.
- Its appearance is colourless and fumes in moist air.
- Its freezing point is 1 °C and its boiling point is 106 °C.
Chemical Properties
- It is highly soluble in chloroform, benzene, carbon, tetrachloride, and carbon disulfide.
- POCl3 can react with HBr to obtain POBr3, in the presence of LEWIS acid catalysts.
- It behaves like a Lewis base by forming adducts with Lewis acids such as titanium, tetrachloride, etc.
- When this compound is treated with excess phenols or alcohols, this compound yields organophosphates or phosphate esters.
- POCl3 reacts with hydrogen bromide in the presence of Lewis-acidic catalysts to produce POBr3.
Things to Remember
- POCl3 is an inorganic compound, it is colourless and forms fumes at room temperature.
- It is used in industries on large scale for the preparation of phosphate esters. It is most commonly used as a dehydrating agent in chemical laborites.
- POCl3 is in a tetrahedral shape.
- It contains 3 phosphorus-chlorine single bonds and one phosphorus-oxygen double bond.
- It has a pungent and musty order.
- It is highly soluble in chloroform, benzene, carbon tetrachloride, and carbon disulfide.
Sample Questions
Ques. What is POCl3 called? (2 marks)
Ans. Phosphor chloride is also known as phosphorus oxychloride. It is a colourless liquid. In moist air, it hydrates and releases choking fumes of hydrogen chloride. Its formula is POCl3.
Ques. Why are there double bonds in POCl3? (3 marks)
Ans. When we calculate chlorine it has zero charges and oxygen has a -1 formula charge.
While moving the two valence electrons into the centre, we've formed a double bond and we can also see that the formal charge of each atom is now zero.
Ques. How can POCl3 be neutralized? (3 marks)
Ans. The relevance quench is the preferred approach of adding post-reaction mixture into ice-water or by adding it in an aqueous base solution.
Quenching the Vilsmeier reaction mixture into ice-water may result in incomplete hydrolysis of POCl3 and a delayed exotherm.
Ques. Is POCl3 a polar molecule? (1 mark)
Ans. This molecule is polar because the molecular geometry of POCl3 is tetrahedral with asymmetric charge distribution around the central atom.
Ques. Is POCl3 acidic or basic? (2 marks)
Ans. It is both acidic and basic. POCl3 also acts as a Lewis base and also forms adducts with a variety of Lewis acids such as titanium tetrachloride:
Cl3PO + TiCl4 → Cl3POTiCl
Ques. Why is POCl3 used? (3 marks)
Ans. POCl3 is used as a dehydrating agent in chemical labs.
- It is also used as a dehydrating agent in the preparation of nitriles from primary amides.
- It is also used as a dehydrating agent in the Bischler-Napieralski reaction.
Ques. Is POCl3 air-sensitive? (3 marks)
Ans. POCl3 is a colourless fuming liquid with a pungent odour.
- It is very toxic by inhalation and corrosive to tissues and metals.
- In moist air, it creates toxic fumes.
- It is a toxic liquid, its density is 14.0 lb/gal.
Ques. What is the oxidation preparation of POCl3? (5 marks)
Ans. The preparation process of oxidation involves oxidation of phosphorus trichloride with oxygen:
PCl3 + O2 → 2 POCl3
An alternative method involves the oxidation of phosphorus trichloride with potassium chlorate:
PCl3 + KClO3 → 3 POCl3 + KCl
Ques. What are the properties of POCl3? (5 marks)
Ans. The properties of POCl3 are:
- Its chemical formula is POCl3
- Its molar mass is 153.33 g/mol
- It is a colourless liquid and becomes fumes in moist air.
- It is pungent and musty in odour.
- It is in the liquid state and its density is 1.645 g/cm3, liquid
Ques. What is the use of POCl3 in organic chemistry? (3 marks)
Ans. POCl3 is used in organic chemistry as it is added to alcohol and a new bond is formed O-P bond.
- It is a strong oxygen phosphorus bond.
- Another bond is also formed called the P-Cl bond; it is also called "chlorophosphate ester".
Ques. What are the functions of POCl3? (3 marks)
Ans. POCl3 is mainly used to produce phosphate esters such as tricresyl phosphate.
- It is manufactured in industries on a large scale.
- It undergoes hydrolysis in moist air and releases phosphoric acid and fumes of hydrogen chloride.
Ques. Is POCl3 a polar or nonpolar molecule? (2 marks)
Ans. This molecule is polar. The molecule geometry is tetrahedral with asymmetric charge distribution around the central atom.
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